Sergio Romero has signed three-year deal with Manchester United.(Getty)

Manchester United have confirmed completing the signing of goalkeeper Sergio Romero.

The 28-year-old was a free agent after his contract at Sampdoria expired earlier this summer. He has now joined the Premier League giants and signed a three-year deal with an option to further extend it by one year on 27 July.

Romero was part of the Argentina squad for the 2014 World Cup campaign in which they were defeated by Germany in the final. He also started in the 2015 Copa America final in July which they lost to Chile.

The Argentine international played under United manager Louis van Gaal during their time at AZ Alkmaar between 2007 and 2009. Romero has expressed his delight as he completed his move to Old Trafford.

"I am absolutely delighted to join Manchester United. To play for the biggest club in the world is a dream come true for me. Louis van Gaal is a fantastic manager and I cannot wait to get started on this new and exciting challenge in my career," Romero told United's official website.

His arrival has given the former Barcelona and Bayern Munich manager several options in the goalkeeping positions. David de Gea, Victor Valdes, Anders Lindegaard and Sam Johnstone are the other four keepers in the squad.

De Gea has one year left on his contract. The 24-year-old has been strongly linked with a move to Real Madrid, according to Spanish newspaper AS. Van Gaal has said that the former Barcelona star has no future at Old Trafford after he failed to follow his philosophy.